The present invention relates to an operating system for hydraulic drive elements of a folding top, in particular of a lowerable folding top of a convertible, which can be actuated by switching apparatus, and, more particularly, to an operating system having drive elements feedable by a pressure source from a pressure medium reservoir via an inlet and connectable to a return to the pressure medium reservoir, switchable directional control valves for distributing pressure generated by the pressure source to the drive elements for moving various parts of the convertible folding top system and having an actuation of the directional control valves corresponding to a given sequence of movements thereof, limit switches for actuating the directional control valves, the limit switches being positively operated by driven parts, and a plurality of driven parts in the form of closures which can be locked and unlocked by double-acting working cylinders and mechanically arrested in a release position thereof against locking by an associated working cylinder.
An electrohydraulic operating system is described in DE 38 26 789 Al. Although the known operating system has a high functional reliability, it is also technically relatively costly. One factor in particular driving up the costs is that a relatively large number of expensive directional control valves are required in the system.
An object of the present invention is to improve operating systems such that a less costly operating system is possible without sacrificing functional reliability.
The foregoing object has been achieved according to the present invention by providing that the pressure source has a feed line arranged to be constantly flow-connected via inlet lines to a rod side of the working cylinders interacting with the closures, as a result of which a pressurization of the pressure medium in the feed line results in an impingement of the working cylinders in a locking advancement direction thereof, and the working cylinders are configured to be differentially actuatable by assigned ones of the directional control valves, by activation of which a drive element of another driven part is switchable along therewith.